ISP Config index is almost completely blank

Hi all,
I uploaded a file to this post. It is a screenshot of how our ISPconfig looks like right now. And nothing of it works. The 'buttons' are dead and lead nowhere when I click them.

While I tried to install a github server, suddenly ISPconfig stopped working showing a 403 - internal server error.
After some usage of google I found a permission setting advice. I tried that advice and this is how the 403 error left, replaced by this almost blank site. And now I spend a few days withouth without knowing how to solve this problem.
I am just a beginner so I don't have enough experience to solve this problem by myself. Can anybody help me?

Ubuntu 14.04 Server using
Apache2 and Webmin
ISPConfig 3 (dunno where to see the detailed version number since ISPconfig Interface doesnt work)